翁源县前汛期两次致灾大暴雨过程对比分析

Comparison and Analysis of Two Disastrous Unusually Hard Rains in the Flood Seasons of Wengyuan County

利用自动观测站逐小时降雨资料、ECMWF的ERA5再分析资料和Micaps探空资料,分别对2010年5月6日(简称“10·05”暴雨过程)和2013年5月15—16日(简称“13·05”暴雨过程)翁源县前汛期两次大暴雨过程进行对比分析,结果表明:两次过程的相同点是发生在低层辐合、高层辐散和低空急流加强的有利环流形势;存在明显的“上冷下暖”对流不稳定配置,且对流层低层假相当位温高值区分别与两次过程中的主要降水时段对应一致,这可为本地暖区暴雨预报提供指示意义;不同点是“10·05”暴雨过程主要受西南暖湿气流的影响,无锋面影响,属于典型的“暖区暴雨”特征;而“13·05”暴雨过程前半段受西南暖湿气流影响,后半段受南支槽、冷空气和切变线的共同影响,属于暖区暴雨加锋面暴雨特征;“10·05”暴雨过程以短时强降水和雷雨大风天气为主,降水效率高,而“13·05”暴雨过程降水持续时间长,列车效应明显。

Using hourly rainfall data from automatic weather stations,ERA5 reanalysis from ECMWF and Micaps radiosonde data,this work compares and analyzes two unusually hard rains in the April-June flood seasons in the county of Wengyuan which happened on May 6,2010 and May 15 to 16,2013,respectively.The results are shown as follows.The two rains are similar in some basic characteristics but quite different in others.They both took place in favorable circulations with low-level convergence,upper-level divergence and enhanced low-level jet streams,accompanied by allocations of significantly unstable convection with cool upper levels versus warm low levels,and high pseudoequivalent potential temperatures in the lower troposphere are temporally consistent with main precipitation in the two rains.They are indicators for local warm-sector hard rain forecasting.The two unusually hard rains differ in what caused them to happen.The 2010 rain was mainly due to a warm and humid southwesterly air current without any frontal effect,having typical characteristics of warm-sector hard rain.The 2013 rain was mainly affected first by a warm and humid southwesterly air current and then jointly by a southerly trough of the westerly,cold air and a shear,possessing the characteristics of both warm-sector and frontal hard rains.The 2010 rain was mainly made up of short-range intense rain and thunderstorm with high raining efficiency while the 2013 rain had extended rain duration with significant train effect.